Method and system for logging a subscriber station onto packet service-service state control function cscf in a communications system

ABSTRACT

The aim of the invention is to provide a particularly simple means of authentication and/or authorization of a station (MS) for the connection and/or service state control function (CSCF). To this end, identification information (IMSI) enabling the authentication/authorization of the station (MS) is provided when registration is requested at the remote access server (RAS).

[0001] The invention relates to a method for registering a station onthe Call State Control Function CSCF in a packet-oriented communicationssystem according to the preamble to claim 1 and a communications systemto carry out the method according to the preamble to claim 8.

[0002] New types of data services such as the packet data service GPRS(General Packet Radio Service) are currently being introduced intoexisting mobile networks based on the GSM standard. Transmission in themobile network does not take place in a connection-oriented orcircuit-switched manner, but in the form of packet data. This type oftransmission more effectively utilizes the given transmission resourcesin the mobile network. The architecture for the packet data serviceassumes (see also FIG. 1) that the fixed or mobile data terminal orcommunications terminal used by the subscriber, e.g. a mobile station,is served at its respective location by a service network node (SGSN:Serving GPRS Support Node). Access to a packet data network is requiredin order to receive or transmit packet data. For this purpose, accessnetwork nodes (GGSN: Gateway GPRS Support Nodes) are provided, which ineach case implement the access to the packet data network, e.g. theInternet, and support a specific packet data protocol e.g. the InternetProtocol (IP). A tunnel, via which the packets are transmitted, isprovided in the mobile network between the service network node and theaccess network node.

[0003] Particularly for third-generation communications systems, e.g.the UMTS (Universal Mobile Telecommunication System), an architecture isprovided for IP-based mobile networks which has an extension of theexisting GPRS architecture in order to provide the call controlcomponents. One of the fundamental new components for this purpose is aCall State Control Function (CSCF). This function performs, inter alia,the call control functions previously performed by Mobile serviceSwitching Centers (MSC). The Call State Control Function CSCF thereforealso serves in particular as a connection control instance formultimedia services in the packet-switching or IP-based core network.The Call State Control Function CSCF which is responsible for a call isdetermined on a data-terminal-specific or subscriber-specific basis,i.e. it is defined by the Home Public Land Mobile Network HPLMN of thesubscriber.

[0004] Registration of data terminals or mobile subscriber stations onthe registration device, e.g. of the packet data network of the 3GPPstandard (3GPP: 3rd Generation Partnership Project) which is currentlybeing set up, is carried out in stages in two instances of the network.The first instance is the packet data service GPRS, whereby theprocedures for the 3GPP system (GPRS Attach and PDP Context Activation)are already described and standardized. The second instance is the CallState Control Function. To register with the Call State Control FunctionCSCF, the subscriber must be authenticated and authorized, i.e. itsidentity and access authorization(s) are checked.

[0005] However, the current standard does not yet provide procedures forselection of the Call State Control Function CSCF or the authorizationand authentication of a subscriber or data station communicating via anygiven IP protocol, e.g. SIP (Session Initiation Protocol) on the CallState Control Function CSCF, i.e. for registering a subscriber andchecking its authorization. However, these procedures are absolutelyessential for secure operation of e.g. packet-oriented 3GPP systems.

[0006] The object of the invention is to propose a method forregistering a station on the Call State Control Function in apacket-oriented communications system and a communications system tocarry out the method.

[0007] This object is achieved by the method with the features of claim1 and the communications system according to the features of claim 8.

[0008] Advantageous designs are described in dependent claims.

[0009] By transmitting the identification information, the method andthe communications system offer a simple facility for authentication andauthorization of a data terminal or station on the Call State ControlFunction of a packet data network.

[0010] Transfer of the international mobile subscriber identity ornumber as the identification information offers a particularly simplesolution, since this is already individually allocated for all stationsand therefore no specific identification information needs to beintroduced.

[0011] Subsequent transfer of an access request corresponding to theidentification information from the Call State Control Function to adevice and/or function for authorization release and/or charge recordingoffers the simple facility for use of a device or function alreadyprovided for authentication/authorization.

[0012] Subsequent exchange of data with the station for authenticationand/or authorization of the station enables a direct request forspecific data, which can be delivered by the station without theintermediate connection of an unnecessarily large number of devices.

[0013] Allowing the device or function for charge recording, followingreceipt of the required data for authentication and/authorization, totransfer an access confirmation corresponding to the identificationinformation to the Call State Control Function enables direct releaseconfirmation to the Call State Control Function.

[0014] Transfer of information relating to authorizations and/orrestrictions of the authorization along with the access confirmation orin addition to this to the Call State Control Function offers thepossibility for the requesting station to release specific resourcesonly. Restrictions may be imposed, for example, in terms of the radiusor diameter of the current location.

[0015] Following the authentication and/or authorization of the stationin the Call State Control Function, the registration and connectionset-up can be continued in the usual manner. No further functions ordevices need to be adapted or introduced.

[0016] Following registration in the Call State -Control Function, thestation MS or terminal can set up any required connections, inparticular connections via any required Internet Protocol telephonyprotocols.

[0017] In the corresponding communications system, the function forproviding subscriber data for charge recording is advantageouslysubordinated to the home subscriber server, to which the Home LocationRegister HLR and the user mobility server can also be subordinated. Thecharge recording itself is advantageously performed in the Call StateControl Function.

[0018] An embodiment is explained in more detail below with reference tothe drawing, in which:

[0019]FIG. 1 shows a schematic radio communications system with aninterface for a packet data service, and

[0020]FIG. 2 shows a flowchart for the connection set-up in theregistration of a radio station in a communications network.

[0021] The communications system shown in FIG. 1 shows a radiocommunications network with devices which enable a packet data serviceGPRS. A mobile station MS of a mobile subscriber, which is connected ina wireless manner via an air interface V to devices of a terrestrialUMTS radio network UTRAN (UMTS Terrestrial Radio Access Network) or itsbase station system BSS with fixed base stations BS, base stationcontrollers and radio network controllers RNC, is shown as an example ofa fixed or mobile communications terminal.

[0022] The connection to a packet-oriented communications network GPRS-Nis set up by the UMTS radio network via the radio network controllerRNC.

[0023] To transmit packet data between the mobile station MS and apacket data network PDN, the communications network GPRS-N has one ormore service network nodes SGSN and at least one access network nodeGGSN connected thereto. The access network node GGSN is connected via aninterface Gi to its own or to an external packet data network PDN,whereas the service network node SGSN is connected to the base stationsystem BSS via an interface Gb. In other words, the communicationssystem has a GPRS packet data network architecture with an IP-basedpacket data network GPRS-N and a UMTS radio network UTRAN on the radioside for communication with mobile and fixed radio stations MS.

[0024] The service network node SGSN contains a packet relay which mapsthe interface Gb to the base station system BSS onto the interface T tothe access network node GGSN, and forwards the data packets in bothdirections.

[0025] For the packet data service GPRS, no connection to packet dataservice network devices or to a packet data access network initiallyexists. In order to use a service, the mobile subscriber currently hasto register with the network in a first step. In doing so, its identityand authorizations are checked in terms of general access to the dataservice GPRS. In the second step, a packet data protocol must beactivated. The packet data service network GPRS-N then provides, forexample, a tunnel T between the relevant service network node SGSN andthe required access network node GGSN to the packet data network PDN.Thereafter, packets can be exchanged via this tunnel T between thesubscriber or the mobile station MS and the external packet data networkPDN.

[0026] In the embodiment described below, the administration andtransmission of data are at least partially supported or controlled by aCall State Control Function CSCF in the Call Control Server CCS. In thecurrently planned third-generation systems, the Call Control Server CCSis connected to the access network node GGSN. However, other connectionsand protocols can also be used.

[0027] An example of a connection set-up between a connection-orientedstation MS and the packet data network GPRS-N is outlined in FIG. 2. Themobile station MS registers, for example, with the packet data networkPDN. In a first method step, a connection set-up is requested by thestation MS in a radio communications network UMTS/UTRAN, within therange of which the station MS is located, and is forwarded to theservice network node SGSN “MS registration/GPRS registration request”.The intermediate steps from the station MS to the service network nodeSGSN are not described in more detail below.

[0028] Thereafter, an authentication procedure takes place between themobile station MS and the service network node SGSN or between theservice network node SGSN and the Home Location Register HLR. Thecurrent location of the mobile station MS is then identified and thesubscriber data inserted between the service network node SGSN and theHome Location Register HLR in a known manner. The request for a packetdata service connection is then submitted by the mobile station MS tothe service network node SGSN and security information is exchangedbetween them. The service network node SGSN and the access network nodeGGSN then create and confirm a packet data connection via the tunnel T,so that a connection to the packet data network PDN is made available tothe mobile station MS. The mobile station MS is correspondingly notifiedby the service network node SGSN that the packet data connection can beactivated.

[0029] In the next step, the mobile station MS requests a registrationon a Remote Access Server RAS as part of the Call State Control FunctionCSCF, according to the present embodiment by transferring its owninternational mobile subscriber identity or number IMSI to the CallState Control Function CSCF. The information identifying which CallState Control Function CSCF is to be activated is transmitted in advanceby the Home Location Register HLR during the GPRS subscriber datainsertion step.

[0030] An access request corresponding to the international mobilesubscriber identity IMSI is then transferred by the Call State ControlFunction CSCF to a charge-metering device or function depending on theAuthentication and Authorization Accounting AAA. Anauthorization-release device or function should also be included insteadof or simultaneously with the charge-metering device or function.

[0031] A direct or indirect information exchange then takes place viathe Call State Control Function CSCF between the device forauthorization/authentication AAA and the mobile station MS, in which therequired data are exchanged, thereby enabling authentication andauthorization of the mobile station MS in theauthorization/authentication device AAA.

[0032] Once the required data have been received, theauthorization/authentication device or function AAA transmits an accessacceptance or access confirmation corresponding to the internationalmobile subscriber identity IMSI to the Call State Control Function CSCF.The authentication and authorization of the subscriber station MS arethus confirmed to the Call State Control Function CSCF.

[0033] The Call State Control Function CSCF can then update the mobilitymanagement (MM) connection in a known manner with the User MobilityServer UMS, and instigate the insertion of subscriber data. Confirmationof the registration on the Remote Access Server is then sent by the CallState Control Function CSCF to the station MS.

[0034] With this type of registration of a station MS on the Call StateControl Function CSCF, the RAS registration request message particularlyincludes identification information which enables authentication of thestation MS. The Home Subscriber Server HSS advantageously includes thefunction AAA for authorization, authentication and optionally for chargerecording, the Home Location Register HLR and the User Mobility ServerUMS. This charge-metering function AAA may then require an additionalrequest to the station MS, e.g. a GSM authentication/authorization or anenquiry to the service network node SGSN of the packet data serviceGPRS, asking whether this subscriber or this station MS is alreadyauthenticated/authorized via the packet data service GPRS. Followingsuccessful authentication, the further procedure, in particular the UMTSprocedure, can take place between the Home Subscriber Server HSS and theCall State Control Function CSCF. On completion of the registration inthe Call State Control Function CSCF, the station MS or terminal can setup any required connections, in particular connections via any requiredInternet Protocol telephony protocols.

1. A method for registering a station (MS) on the Call State ControlFunction (CSCF) of a packet-oriented communications system (UMTS/GPRS),whereby the station (MS) requests a registration on a remote accessserver (RAS) of the Call State Control Function (CSCF), characterized inthat the request for registration on the remote access server (RAS)includes identification information (IMSI) which enables authenticationand/or authorization of the station (MS).
 2. The method as claimed inclaim 1, in which an international mobile subscriber identity or number(IMSI) is transferred as identification information (IMSI).
 3. Themethod as claimed in claim 1 or 2, in which, from the Call State ControlFunction (CSCF), an access request corresponding to the identificationinformation (IMSI) is then transferred to a device and/or function forauthorization release and/or charge recording (AAA).
 4. The method asclaimed in a preceding claim, in which data for authentication and/orauthorization of the station (MS) are then exchanged with the station(MS).
 5. The method as claimed in claim 3, in which, once the requireddata for authentication and/or authorization of the station (MS) havebeen received, the charge-metering device or function (AAA) transfers anaccess confirmation corresponding to the identification information(IMSI) to the Call State Control Function (CSCF).
 6. The method asclaimed in claim 5, in which information relating to the authorizationand/or restrictions of the authorization is transferred along with, orin addition to, the access confirmation to the Call State ControlFunction (CSCF).
 7. The method as claimed in a preceding claim, in whichthe registration and connection set-up are continued following theauthentication and/or authorization of the station (MS) in the CallState Control Function (CSCF).
 8. A communications system, in particularto carry out a method as claimed in a preceding claim, with an at leastpartially packet-oriented communications network (UMTS/GPRS), at leastone station (MS) which can communicate via an interface (V) with thecommunications network (UMTS) at least one Call State Control Function(CSCF) of the packet-oriented part (GPRS) of the communications systemto control at least some services in a connection of the station (MS)with a packet data network (PDN) via the interface (V), characterized bya device (HSS) for authentication and/or authorization of the station(MS) in the Call State Control Function (CSCF) depending onidentification information (IMSI) transmitted during the request forregistration on a remote access server (RAS).
 9. The communicationssystem as claimed in claim 8, in which the device (HSS) forauthentication and/or authorization is directly connected to the CallState Control Function (CSCF).
 10. The communications system as claimedin claim 8 or 9, in which the device (HSS) for authentication and/orauthorization has a charge-metering function.